NJDA's
beneficial insect laboratory in Ewing, in cooperation
with NJDEP's Division of Parks and Forestry and USDA's
Forest Service (USFS) have released a natural predator
of a devastating pest of hemlock trees in four locations
around the state to test the predators' ability to
control the pest.

Approximately 30,000 of the tiny natural
predators, a black ladybug, have been raised in the Ewing laboratory
and released to combat hemlock wooly adelgids, minute sap-sucking
insects that can turn a healthy, 100- foot hemlock into a skeleton
in just a few short years. The effectiveness and hardyness of the
ladybug will be monitored over the next several years. Hemlock wooly
adelgids are found throughout the state's 25,000 acres of hemlock
forests. Without a natural predator, and with conventional treatment
methods impossible in the mostly inaccessible areas where hemlocks
grow, the pest, native to Japan and China, has spread from Massachusetts
to North Carolina since the first adelgid landed in the United States
in the 1920s. Since 1988, NJDA has been working with USFS and the
state Bureau of Forestry on an impact study to determine the pest's
effect on Garden State hemlock forests. In some of the study plots,
hemlock mortality rose from under 10 percent to over 60 percent in
less than four years. There has been no practical way to control
the pest since the infested forested areas are usually inaccessible
to spray equipment and aerial sprays cannot effectively reach the
majority of the pests through the forest canopy. The voracious ladybug
released last month was discovered in 1990 by Dr. Mark McClure of
the Connecticut Agricultural Experiment Station while he was surveying
for hemlock adelgid predators in Japan. His additional research indicated
that the ladybug does reduce adelgid populations when released in
hemlock forests.

Last year NJDA scientists acquired
a small colony of the tiny predator ladybugs from McClure and began
raising them in the laboratory. Once released, scientists expect
the beetles will begin to feed on the wooly adelgids, reproduce and
spread to neighboring trees through short flights or on strong breezes.